Support element hiding emulation exception rules

[sebastian]

Background

With #5287 we implemented a new kind of element hiding filters which are implemented differently in order to allow some more advanced filtering. These filters, however, cannot be whitelisted yet, while regular element hiding filters like ##.ad would be whitelisted by an exception rule like #@#.ad.

What to change

If there is a filter like example.com#?@#.ad, the filter example.com#?#.ad should not have any effect.

[fhd]

It seems that regular element hiding exceptions work for element hiding emulation rules as well. Here's what I tried in Chrome with the current devbuild:

1. Add the following custom filter: testpages.adblockplus.org#?#.abp-testsuite-fail
2. Go to ​https://testpages.adblockplus.org/en/testsuite/05
3. Verify that the element is hidden (i.e. the box is green)
4. Add the following custom filter: testpages.adblockplus.org#@#.abp-testsuite-fail
5. Go to ​https://testpages.adblockplus.org/en/testsuite/05
6. Verify that the element is not hidden (i.e. the box is red)

[trev]

In fact, we are explicitly testing that element hiding exception apply to emulation rules as well. IMHO, that's sufficient as a solution, introducing a special syntax for emulation exceptions doesn't provide any additional value. So I am closing this issue, feel free to comment with your reasoning if you disagree.

[sebastian]

For reference, this feature request was initially brought up by Arthur, and for some reason both of us just assumed that regular element hiding exception rules wouldn't work. But since they apparently do, I agree, that this issue should be closed without a fix.